WALE LIMB MICROSCOPE

MODEL: 'NEW STUDENT MICROSCOPE'

c. 1886-1888

Maker: BAUSCH & LOMB

Serial number: NONE

DESCRIPTION

This microscope is seated on a 'continental' or 'horseshoe' foot, a bit differently than Wale's original model which was a Y-shaped tripod which is raised near its center. The two sides of the horseshoe are held together by a system quite similar to Wale's original with a guide pin in the rear and the main screw (with its large lacquered brass control knob) regulating the tension on the Wale limb. As in Wale's original, and unlike e.g. the Swift model, the foot is all cast. This is in contrast to Swift's Wale where the foot is more finely finished and the groove for the limb is machined, resulting in a much finer inclination mechanism. The only signature on this instrument is the patent date of January 21, 1879 on a small brass plaque at the top of the limb below the pinion box (removed in the image for clarity). This patent relates to one of Ernst Gundlach's fine adjustment designs from when he was working for Bausch & Lomb. The stage is attached to the bottom of the limb by a single heavy screw.

On the underside of the stage a wheel of apertures made of hard rubber* (also known as Vulcanite) is attached. The aperture wheel can be swung completely out of the optical axis. The wheel offers a choice of 4 aperture sizes. There is no stop to register these. A swinging tailpiece with its axis at the level of the stage, carries a single-sided gimbaled concave mirror at its distal end. This allows oblique as well as top lighting from above. The round stage has holes for stage clips. Coarse focus is by straight rack and pinion, fine is the Gundlach fine focus as noted above. There is a single but matching low power objective and a single brass eyepiece. The drawtube is nickel plated and has a single calibration mark about half way up. The drawtube has a threaded lower end to accept an erecting lens or other similarly-positioned accessory.

There is a finely divided scale and vernier for registering the position of the main tube when focused. This option is not mentioned in the catalog entry I have seen, nor is it found on other examples of this microscope that I am aware of. This is a common addition to many microscopes however, so this was a commonly requested addition for most microscope makers, and might not be listed separately.

*Vulcanite or hard rubber, was a product frequently used by Bausch & Lomb, sometimes as the top layer of the stage, but also as the housing for a type of camera lucida, and especially for eyeglass frames. Some other optical parts were occasionally also encased in this substance, though the wheel of aperture use may be the most common. For B & L, it replaced the earlier plastic-like substance derived from a certain tree sap known as 'Gutta Percha' which was also in use in the 19th century. I am not certain that this was superior in any way to gutta percha, as both are somewhat brittle. When used as a coating for the stage (not seen on this model), Vulcanite did insulate it a bit and lessen the tendency of a warmed subject to change temperature rapidly. This use can be seen in the Swift 'Bacteriological' Microscope.

HISTORY OF THE B & L WALE LIMB MICROSCOPE

George Wale has his name associated with the inclination mechanism found on this and many other maker's microscopes. He invented it about 1878. For more information about Wale and the invention see the Wale History section on the page about his original 'New Working Microscope'

Bausch & Lomb bought Wale's business in 1880, but did not at that time continue the design of his original. It was not until 1886, as reported in the JRMS of that year, that B & L made their version of the stand as shown on this page. It was apparently only made for a short time, perhaps two or three years. For this reason, the B & L Wale limb microscope seen here is very uncommon today.

Although originally pictured with simple push-pull coarse focus, rack and pinion coarse focus was an option offered in the catalog, and this option is part of the example shown on this web page. A short survey of some of my fellow collectors reveals more examples survive with this option than without it. For an example without the rack and pinion, see Dr Crovetto's example.
Although Wale invented this type of inclination, and B & L bought Wale's business, it is interesting that in their catalog listing, they gave no credit to Wale.

Although many Wale-limb microscopes were promoted as 'Student' models and were meant to be inexpensive, expensive and complex variations were also made. Some of these complex (and expensive) variations are pictured on this website either with real examples or engravings. These included the B & L concentric, the Ross-Wenham Radial, and a a much later Swift 'Symposium' model. The simpler, but still well made, Swift Swift 'Improved Wales Limb' is also on this site. For an example of a Wale Limb microscope by Schrauer, see the example on Allan Wissner's Web site. Many early 20th century 'Radial' variations of high complexity were also made by R. and J. Beck.